ALBERT

Notes: Aquifer storage and recovery (ASR) is an emerging and effective management technique in reclaiming and reusing waste water. During ASR, attenuation processes such as sorption and degradation may play an important role in removing trace organic contaminants in injected waste water. This study mainly investigated the role of treated sewage effluent injectant (the waste water injected into the aquifer) on degradation of two endocrine disrupting compounds, 17β-estradiol (E2) and 17α-ethynylestradiol (EE2), in the laboratory by comparing their behavior in incubation media—aquifer sediment/ground water slurry from the Bolivar experimental ASR site in South Australia and sediment/effluent slurry. Biodegradation of the two compounds in the sediment/ground water media (1:1, w/w) and in the sediment/effluent media (1:1, w/w) were conducted under aerobic and anaerobic conditions at 20°C. In both incubation media, E2 showed a rapid biodegradation with a DT50 value (time for 50% loss) of ∼2 days under aerobic conditions. E2 degraded slowly in both aquifer media under anaerobic conditions; however, the anaerobic degradation was noted to be somewhat faster in the sediment/effluent media. In contrast, EE2 was found to be resistant to biodegradation and remained almost unchanged within 70 days under anaerobic conditions in both incubation media. The mobility of the two compounds in the aquifer would depend on their sorption. The sorption coefficients measured on the aquifer sediment were 7.7 ± 3.4 L/kg for E2 and 10.6 ± 5.1 L/kg for EE2 using batch equilibration methods. The corresponding retardation factors were calculated to be 25 for E2 and 34 for EE2 based on the physical properties of the aquifer material in the Bolivar ASR site. This study showed that while E2 has modest sorption affinity for aquifer material, it is rapidly biodegraded with or without the supplement of effluent under aerobic conditions. Under anaerobic conditions, the relative rate of E2 degradation was slightly enhanced due to the presence of effluent in the incubation media. EE2 on the other hand was found to be persistent in this study under both aerobic and anaerobic conditions, as well as in the presence of effluent.

Notes: A key factor in the long-term viability of aquifer storage recovery (ASR) is the extent of mineral solution interaction between two dissimilar water types and consequent impact on water quality and aquifer stability. We collected geochemical and isotopic data from three observation wells located 25, 65, and 325 m from an injection well at an experimental ASR site located in a karstic, confined carbonate aquifer in South Australia. The experiment involved five major injection cycles of a total of 2.5 × 105 m3 of storm water (total dissolved solids [TDS] ∼ 150 mg/L) into the brackish (TDS ∼2400 mg/L) aquifer. ∼60% of the mixture was pumped out during the fifth year of the experiment. The major effect on water quality within a 25 m radius of the injection well following injection of storm water was carbonate dissolution (35 ± 6 g of CaCO3 dissolved/m3 of aquifer) and sulfide mineral oxidation (50 ± 10 g as FeS2/m3 after one injection). 〈 0.005% of the total aquifer carbonate matrix was dissolved during each injection event, and ∼0.2% of the total reduced sulfur. Increasing amounts of ambient ground water was entrained into the injected mixture during each of the storage periods. High 14CDIC activities and slightly more negative δ13CDIC values measured immediately after injection events show that substantial CO2(aq) is produced by oxidation of organic matter associated with injectant. There were no detectable geochemical reactions while pumping during the recovery phase in the fifth year of the experiment.

Notes: An innovative and nondestructive method to measure the hydraulic conductivity of drill core samples in horizontal and vertical directions within a triaxial cell has been developed. This has been applied to characterizing anisotropy and heterogeneity of a confined consolidated limestone aquifer. Most of the cores tested were isotropic, but hydraulic conductivity varied considerably and the core samples with lowest values were also the most anisotropic. Hydraulic conductivity decreased with increasing effective stress due to closure of microfractures caused by sampling for all core samples. This demonstrates the importance of replicating in situ effective stresses when measuring hydraulic conductivity of cores of deep aquifers in the laboratory.

Notes: [Auszug] Minerals in soil contain many small pores, which has led to the suggestion that trees are able to 'mine' essential nutrients such as calcium through their association with symbiotic mycorrhizae, thereby bypassing the exchangeable calcium pool in the soil. On the basis of the ...

Notes: 1. Within a lake district of relatively homogeneous geomorphology, the responses of lakes to climate are influenced by the complexity of the hydrogeologic setting, position in the landscape, and lake-specific biological and physical features. We examined lake chemical responses to drought in surface water- and groundwater-dominated districts to address two general questions. (1) Are spatial patterns in chemical dynamics among lakes uniform and synchronous within a lake district, suggesting broad geomorphic controls; variable in a spatially explicit pattern, with synchrony related to landscape position, suggesting hydrologic flowpath controls; or spatially unstructured and asynchronous, suggesting overriding control by lake-specific factors? (2) Are lake responses to drought a simple function of precipitation quantity or are they dictated by more complex interactions among climate, unique lake features, and hydrologic setting?2. Annual open-water means for epilimnetic concentrations of chloride, calcium, sulfate, ANC, DOC, total nitrogen, silica, total phosphorus, and chlorophyll a measured between 1982 and 1995 were assembled for lakes in the Red Lake and ELA districts of north-western Ontario, the Muskoka – Dorset district in south-central Ontario, and the Northern Highland district of Wisconsin. Within each district, we compared responses of lakes classified by landscape position into highland or lowland, depending on relative location within the local to regional hydrologic flow system. Synchrony, defined as a measure of the similarity in inter-annual dynamics among lakes within a district, was quantified as the Pearson product-moment correlation (r) between two lakes with observations paired by year. To determine if solute concentrations were directly related to interannual variations in precipitation quantity, we used regression analysis to fit district-wide slopes describing the relationship between each chemical variable and annual (June to May) and October to May (Oct–May) precipitation.3. Among lakes in each of the three Ontario districts, the pattern of chemical response to interannual shifts in precipitation was spatially uniform. In these surface water- dominated districts, solute concentrations were generally a simple function of precipitation. Conservative solutes, like calcium and chloride, tended to be more synchronous and were negatively related to precipitation. Solutes such as silica, total phosphorus, and chlorophyll a, which are influenced by in-lake processes, were less synchronous and relationships with precipitation tended to be positive or absent.4. In the groundwater-dominated Northern Highland lakes of Wisconsin, we observed spatial structure in drought response, with lowland lakes more synchronous than highland lakes. However, there was no evidence for a direct relationship between any solute and precipitation. Instead, increases in the concentration of the conservative ion calcium during drought were not followed by a symmetrical return to pre-drought conditions when precipitation returned to normal or above-average values.5. For calcium, time lags in recovery from drought appeared related to hydrologic features in a complex way. In the highland Crystal Lake, calcium concentrations tracked lake stage inversely, with a return to pre-drought concentrations and lake stage five years after the drought. This pattern suggests strong evaporative controls. In contrast, after five years of normal precipitation, calcium in the lowland Sparkling Lake had not returned to pre-drought conditions despite a rebound in lake stage. This result suggests that calcium concentrations in lowland lakes were controlled more by regional groundwater flowpaths, which track climatic signals more slowly.6. Temporal dynamics driven by climate were most similar among lakes in districts that have a relatively simple hydrology, such as ELA. Where hydrologic setting was more complex, as in the groundwater-dominated Northern Highland of Wisconsin, the expression of climate signals in lakes showed lags and spatial patterns related to landscape position. In general, we expect that landscape and lake-specific factors become increasingly important in lake districts with more heterogeneous hydrogeology, topography or land use. These strong chemical responses to climate need to be considered when interpreting the responses of lakes to other regional disturbances.

Notes: 1. We explored patterns of limnological variables (physical, chemical and biological) with relation to landscape position (expressed as lake order) in 86 study lakes located on shield bedrock in south-central Ontario, Canada.2. Using anovas with lake order as the categorical variable, landscape position explained significant amounts of variation in major ion chemistry, physical and catchment characteristics, hypolimnetic oxygen, and community composition in algal (diatom, chrysophyte) and invertebrate (chironomid) assemblages preserved in surficial sediments. Several nutrient variables (TP, total phosphorus and TN, total nitrogen) and dissolved organic carbon did not have significant relationships with lake order.3. The strongest relationships with lake order (as a fraction of variation explained in anovas) included silica concentrations (r2 = 0.40) and SO4 (r2 = 0.29) concentrations, surface area (r2 = 0.50) and hypolimnetic oxygen (r2 = 0.29).4. Bedrock geology (carbonate metasedimentary versus non-carbonate bedrock) had strong influences on spatial gradients of pH and major ion chemistry. It was difficult to separate geological influences from spatial influences on limnological variables in this study, as drainage patterns in the region are highly influenced by surface features of underlying geological formations because of the very thin glacial till or exposed bedrock that exists in most catchments.5. Patterns of limnological variables indicated that low-order, headwater lakes had the lowest concentrations of major ions, and, from algal inferences of pH change, had been most susceptible to acidic deposition. High-order, downstream lakes were larger and deeper, and had higher concentrations of hypolimnetic oxygen, indicating that optimal lake trout habitat was primarily located in high-order lakes.6. Variance partitioning analyses indicated that lake order as a metric of landscape position explained comparable portions of community variation in algal and invertebrate assemblages compared with geographic position (latitude, longitude) and Cartesian coordinate position (e.g. x, y, x2, y2, etc.) metrics. Lake order explained more community variation in chironomid assemblages compared with other landscape metrics, possibly because of the strong relationships between lake order and lake morphometry variables.

Notes: [Auszug] The theory tested here is a simple mechanistic method for predicting catchment response to changing acid anion con-centrations directly from runoff chemistry8. The governing equations resemble those underlying many acidification com-puter models9"12, but they are solved analytically, yielding ...